There is a Military program called E-purge that is desigend to do exactly that.
It is on a cd-rom, all you do is put it in your drive, run the .exe file on it and let it do the rest.
When i seen it, it took just over 12 mins to wipe a 60GB HDD!!

As it is a Military program though im not sure if it is available on civi street!
I was shown this about two years ago so it might be available by now.

I googled e-purge and a few results came up but nothing that sounds like the program i am talking about!

Hope you can find it!